US8435861B2 - Method of manufacturing a semiconductor device having different kinds of insulating films with different thicknesses - Google Patents
Method of manufacturing a semiconductor device having different kinds of insulating films with different thicknesses Download PDFInfo
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- US8435861B2 US8435861B2 US12/957,627 US95762710A US8435861B2 US 8435861 B2 US8435861 B2 US 8435861B2 US 95762710 A US95762710 A US 95762710A US 8435861 B2 US8435861 B2 US 8435861B2
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
- H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
- H01L21/82—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components
- H01L21/822—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components the substrate being a semiconductor, using silicon technology
- H01L21/8232—Field-effect technology
- H01L21/8234—MIS technology, i.e. integration processes of field effect transistors of the conductor-insulator-semiconductor type
- H01L21/8238—Complementary field-effect transistors, e.g. CMOS
- H01L21/823857—Complementary field-effect transistors, e.g. CMOS with a particular manufacturing method of the gate insulating layers, e.g. different gate insulating layer thicknesses, particular gate insulator materials or particular gate insulator implants
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
- H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
- H01L21/82—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components
- H01L21/822—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components the substrate being a semiconductor, using silicon technology
- H01L21/8232—Field-effect technology
- H01L21/8234—MIS technology, i.e. integration processes of field effect transistors of the conductor-insulator-semiconductor type
- H01L21/8238—Complementary field-effect transistors, e.g. CMOS
- H01L21/823878—Complementary field-effect transistors, e.g. CMOS isolation region manufacturing related aspects, e.g. to avoid interaction of isolation region with adjacent structure
Definitions
- the present invention relates to methods of manufacturing a semiconductor device.
- MIS Metal Insulator Semiconductor
- transistors with different driving voltages have gate insulating films with different thicknesses, for reasons including the difference in gate withstands a voltage requirement between and among the transistors.
- a known method for preparing gate insulating films of different thicknesses is as follows.
- a first silicon dioxide film is formed by thermal oxidation or some other method on first and second transistor formation areas.
- the first transistor formation area is an area on which a thinner gate insulating film is formed, whereas the second one is an area on which a thicker gate insulating film is formed.
- the portion of the first silicon dioxide film lying on the first transistor formation area is selectively removed.
- a second silicon dioxide film is formed by thermal oxidation or some other method on the first transistor formation area, while the portion of the first silicon dioxide film that corresponds to the second transistor formation area is further oxidized; a third silicon dioxide film is formed as a film thicker than the first silicon dioxide film.
- the first transistor formation area is covered with the second silicon dioxide film that serves as a first gate insulating film
- the second transistor formation area is covered with the third silicon dioxide film that serves as a second gate insulating film.
- a semiconductor device having three or more kinds of gate insulating films of different thicknesses may also be made, by repeating the procedure described above.
- a method of manufacturing a semiconductor device includes oxidizing a surface of a semiconductor substrate to form a first insulating film covering a first area, a second area, and a third area of the semiconductor substrate; removing the portions of the first insulating film lying on the first area and the second area; oxidizing the surface of the semiconductor substrate to form a second insulating film covering the first area and the second area and further oxidizing the third area covered with the first insulating film; removing the portion of the second insulating film lying on the second area and the portion of the first insulating film lying on the third area; and oxidizing the surface of the semiconductor substrate to form a first gate insulating film covering the second area and the third area and further oxidizing the first area covered with the second insulating film to form a second gate insulating film, the second gate insulating film covering the first area is thicker than the first gate insulating film.
- FIG. 1 is a schematic cross-sectional diagram illustrating the structure of a semiconductor device according to an embodiment.
- FIGS. 2A to 2P are cross-sectional diagrams illustrating operations of a manufacturing method of a semiconductor device according to the embodiment.
- FIGS. 3A to 3H are cross-sectional diagrams illustrating operations of a manufacturing method of a semiconductor device according to another form of the embodiment, which is described later.
- FIG. 4 illustrates plots of the time of treatment with hydrofluoric acid versus the resultant thickness of the silicon dioxide film treated.
- FIG. 5 illustrates magnified plots of the time of treatment with hydrofluoric acid versus the resultant thickness of the silicon dioxide film treated.
- the inventors have conducted extensive research on semiconductor devices having different kinds of gate insulating films with different thicknesses, finding some problems: In some MIS transistors, reduced thicknesses of gate insulating films may cause size variation among gate electrodes, decreased reliability of the gate insulating films, and so forth.
- FIG. 1 is a schematic cross-sectional diagram illustrating the structure of a semiconductor device according to this embodiment.
- FIGS. 2A to 2P are cross-sectional diagrams illustrating operations of a method of manufacturing the semiconductor device.
- FIGS. 3A to 3H are cross-sectional diagrams illustrating operations of a method of manufacturing a semiconductor device according to an aspect of the embodiment, which is described later.
- FIGS. 4 and 5 illustrate plots of the time of treatment with hydrofluoric acid versus the resultant thickness of the silicon dioxide film treated.
- a silicon substrate 10 has an element-partitioning film 12 formed thereon.
- the element-partitioning film 12 defines areas on which elements are formed.
- the element formation areas are referred to as follows, from left to right: an N-type low-voltage transistor formation area (or a second area), a P-type low-voltage transistor formation area (or a third area), an N-type medium-voltage transistor formation area (or a first area), a P-type medium-voltage transistor formation area (also included in the first area), an N-type high-voltage transistor formation area (a fourth area), and a P-type high-voltage transistor formation area (also included in the fourth area).
- the low-voltage transistor formation areas include an area on which a low-voltage transistor is formed, and the common collector voltage V CC to drive this transistor is, for example, 1.2 V.
- the medium-voltage transistor formation areas include an area on which a medium-voltage transistor is formed, and V CC to drive this transistor is, for example, 3.3 V.
- the high-voltage transistor formation areas include an area on which a high-voltage transistor is formed, and V CC to drive this transistor is, for example, 5.0 V. Note that there is no particular limitation on the driving voltage of each transistor.
- the silicon substrate 10 has a P well 24 , the element formation area is covered with a gate insulating film 36 that has a gate electrode 48 formed thereon, and a bottom portion of the gate electrode 48 is in between N-type source/drain areas 60 .
- the silicon substrate 10 has an N well 26 , the element formation area is covered with a gate insulating film 36 that has a gate electrode 48 formed thereon, and a bottom portion of the gate electrode 48 is in between P-type source/drain areas 62 .
- the silicon substrate 10 has a P well 20 , the element formation area is covered with a gate insulating film 40 that has a gate electrode 48 formed thereon, and a bottom portion of the gate electrode 48 is in between N-type source/drain areas 60 .
- the gate insulating film 40 is preferably thicker than the gate insulating film 36 .
- the silicon substrate 10 has an N well 22 , the element formation area is covered with a gate insulating film 40 that has a gate electrode 48 formed thereon, and a bottom portion of the gate electrode 48 is in between P-type source/drain areas 62 .
- the gate insulating film 40 is preferably thicker than the gate insulating film 36 .
- the silicon substrate 10 has a P well 16 , the element formation area is covered with a gate insulating film 38 that has a gate electrode 48 formed thereon, and a bottom portion of the gate electrode 48 is in between N-type source/drain areas 60 .
- the gate insulating film 38 is preferably thicker than the gate insulating film 40 .
- the silicon substrate 10 has an N well 18 , the element formation area is covered with a gate insulating film 38 that has a gate electrode 48 formed thereon, and a bottom portion of the gate electrode 48 is in between P-type source/drain areas 62 .
- the gate insulating film 38 is preferably thicker than the gate insulating film 40 .
- the gate electrode 48 is sandwiched between sidewall insulating films 54 .
- a semiconductor device has three kinds of transistors with gate insulating films of different thicknesses.
- FIGS. 2A to 2P a method of manufacturing a semiconductor device according to the embodiment is detailed with reference to FIGS. 2A to 2P .
- a silicon substrate 10 is covered with an element-partitioning film 12 , which is formed by shallow trench isolation (STI) or some other method. As described above, the element-partitioning film 12 defines areas on which elements are formed.
- STI shallow trench isolation
- a silicon dioxide film is formed by thermal oxidation or some other method to have a thickness of, for example, 10 nanometers (nm).
- the silicon substrate 10 has its element formation areas, which are defined by the element-partitioning film 12 , covered with the silicon dioxide film; this film is referred to as a sacrificial oxide film 14 ( FIG. 2A ).
- a photoresist film is photolithographically formed to cover the areas excluding the N-type high-voltage transistor formation area. Ions are implanted with this photoresist film as the mask. For example, boron ions (B + ) are implanted under the following conditions: acceleration energy: 255 kiloelectron volts (keV); the number of ions implanted: 3.3 ⁇ 10 13 cm ⁇ 2 ; and then under the following conditions: acceleration energy: 180 keV; the number of ions implanted: 1.8 ⁇ 10 13 cm ⁇ 2 . This series of implantations creates a P well 16 in the N-type high-voltage transistor formation area.
- a photoresist film is photolithographically formed to cover the areas excluding the P-type high-voltage transistor formation area. Ions are implanted with this photoresist film as the mask. For example, phosphorus ions (P + ) are implanted under the following conditions: acceleration energy: 500 keV; the number of ions implanted: 1.8 ⁇ 10 13 cm ⁇ 2 ; and then arsenic ions (As + ) are implanted under the following conditions: acceleration energy: 125 keV; the number of ions implanted: 1.2 ⁇ 10 12 cm ⁇ 2 . This series of implantations creates an N well 18 in the P-type high-voltage transistor formation area.
- P + phosphorus ions
- As + arsenic ions
- a photoresist film is photolithographically formed to cover the areas excluding the N-type medium-voltage transistor formation area. Ions are implanted with this photoresist film as the mask. For example, boron ions (B + ) are implanted under the following conditions: acceleration energy: 150 keV; the number of ions implanted: 3.0 ⁇ 10 13 cm ⁇ 2 ; and then under the following conditions: acceleration energy: 15 keV; the number of ions implanted: 2.0 ⁇ 10 12 cm ⁇ 2 .
- the ion implantation with the higher energy level is for the main purpose of creating a well and may be called well ion implantation, whereas that with the lower energy level is for the main purpose of adjusting the transistor threshold voltage and may be called channel ion implantation.
- This series of implantations creates a P well 20 in the N-type medium-voltage transistor formation area.
- a photoresist film is photolithographically formed to cover the areas excluding the P-type medium-voltage transistor formation area. Ions are implanted with this photoresist film as the mask. For example, phosphorus ions (P + ) are implanted under the following conditions: acceleration energy: 360 keV; the number of ions implanted: 3.0 ⁇ 10 13 cm ⁇ 2 ; and then arsenic ions (As + ) are implanted under the following conditions: acceleration energy: 125 keV; the number of ions implanted: 3.2 ⁇ 10 12 cm ⁇ 2 .
- P + phosphorus ions
- As + arsenic ions
- the ion implantation with the higher energy level is for the main purpose of well ion implantation, whereas that with the lower energy level is for the main purpose of channel ion implantation.
- This series of implantations creates an N well 22 in the P-type medium-voltage transistor formation area.
- a photoresist film is photolithographically formed to cover the areas excluding the N-type low-voltage transistor formation area. Ions are implanted with this photoresist film as the mask.
- boron ions B +
- acceleration energy 150 keV
- indium ions In +
- indium ions are implanted once again, under the following conditions: acceleration energy: 120 keV
- boron ions are implanted once again, under the following conditions: acceleration energy: 15 keV; the number of ions implanted: 3.5 ⁇ 10 13 cm ⁇ 2 .
- the series of ion implantations with higher energy levels is for the main purpose of well ion implantation, whereas the ion implantation with the lowest energy level is for the main purpose of channel ion implantation.
- This series of implantations creates a P well 24 in the N-type low-voltage transistor formation area.
- a photoresist film is photolithographically formed to cover the areas excluding the P-type low-voltage transistor formation area. Ions are implanted with this photoresist film as the mask. For example, phosphorus ions (P + ) are implanted under the following conditions: acceleration energy: 360 keV; the number of ions implanted: 3.0 ⁇ 10 13 cm ⁇ 2 ; and then arsenic ions (As + ) are implanted under the following conditions: acceleration energy: 125 keV; the number of ions implanted: 3.5 ⁇ 10 12 cm ⁇ 2 .
- P + phosphorus ions
- As + arsenic ions
- the ion implantation with the higher energy level is for the main purpose of well ion implantation, whereas that with the lower energy level is for the main purpose of channel ion implantation.
- This series of implantations creates an N well 26 in the P-type low-voltage transistor formation area ( FIG. 2C ).
- the photoresist film is described as being photolithographically formed, other suitable formation methods may also be used. Also, the order of the formation of the P wells 16 , 20 , and 24 and N wells 18 , 22 , and 26 is not limited to those described above. Substantially simultaneous ion implantations (e.g., well ion implantations for low-voltage and medium-voltage transistors) are allowed.
- the sacrificial oxide film 14 is removed by wet etching with hydrofluoric acid or some other method ( FIG. 2D ).
- a silicon dioxide film 28 is formed on the silicon substrate 10 to cover the element formation areas, which are defined by the element-partitioning film 12 , by thermal oxidation or some other method ( FIG. 2E ).
- the film thickness reached is, for example, 10 nm.
- a photoresist film 30 is photolithographically formed to cover the high-voltage transistor formation areas and the P-type low-voltage transistor formation area, leaving the medium-voltage transistor formation areas and the N-type low-voltage transistor formation area exposed.
- the portion of the silicon dioxide film 28 lying on the medium-voltage transistor formation areas and P-type low-voltage transistor formation area are selectively removed, with the photoresist film 30 as the mask, by wet etching with hydrofluoric acid or some other method ( FIG. 2F ).
- the photoresist film 30 is removed by ashing or some other method.
- the silicon substrate 10 is oxidized under heat by thermal oxidation or some other method so that a silicon dioxide film 32 is formed to cover the element formation areas in the medium-voltage transistor formation areas and N-type low-voltage transistor formation area ( FIG. 2G ).
- the film thickness reached is, for example, 6 nm.
- oxidation proceeds in the high-voltage transistor formation areas and the P-type low-voltage transistor formation area as well, increasing the thickness of the silicon dioxide film 28 to about 14 nm.
- a photoresist film 34 is photolithographically formed to cover the medium-voltage and high-voltage transistor formation areas, leaving the low-voltage transistor formation areas exposed.
- the portion of the silicon dioxide film 32 lying on the N-type low-voltage transistor formation area and the portion of the silicon dioxide film 28 lying on the P-type low-voltage transistor formation area are selectively removed, with the photoresist film 34 as the mask, by wet etching with hydrofluoric acid or some other method ( FIG. 2H ).
- the photoresist film 34 is removed by ashing or some other method.
- the silicon substrate 10 is oxidized under heat by thermal oxidation or some other method so that a gate insulating film, which is a silicon dioxide film, is formed to cover the element formation areas in all transistor formation areas ( FIG. 2I ).
- a gate insulating film 36 is formed with a thickness of, for example, 2 nm.
- a gate insulating film 38 is formed with a thickness of, for example, 14 nm.
- a gate insulating film 40 is formed with a thickness of, for example, 6.1 nm.
- oxidation proceeds also in the high-voltage transistor formation areas, which are covered with the silicon dioxide film 28 , and in the P-type low-voltage transistor formation area, which is covered with the silicon dioxide film 32 .
- the increase in film thickness brought about by oxidation is negligibly small for the silicon dioxide film 28 and as small as 0.1 nm for the silicon dioxide film 32 .
- a polycrystalline silicon film 42 or some other kind of conductive film that may provide gate electrodes is formed by chemical vapor deposition (CVD) or some other deposition method to cover the whole surface ( FIG. 2J ).
- the polycrystalline silicon film 42 is covered by spin coating or some other method with a BARC (bottom anti-reflective coating) film 44 and a photoresist film 46 ( FIG. 2K ).
- BARC bottom anti-reflective coating
- the photoresist film 46 is photolithographically patterned to draw the intended pattern of gate electrodes ( FIG. 2L ).
- the polycrystalline silicon film 42 is patterned by dry etching, with the patterned photoresist film 46 as the mask. As a result, each transistor formation area holds a gate electrode 48 , which is based on polycrystalline silicon, formed thereon ( FIG. 2M ).
- a photoresist film is formed to cover the P-type transistor formation areas, leaving the N-type transistor formation areas exposed. Ions are implanted with this photoresist film and the gate electrodes 48 as masks. This ion implantation creates N-type dopant diffusion areas 50 for extension in the silicon substrate 10 in such a manner that the diffusion areas put the basement of the gate electrode 48 for each N-type transistor between them.
- a photoresist film is formed to cover the N-type transistor formation areas, leaving the P-type transistor formation areas exposed. Ions are implanted with this photoresist film and the gate electrodes 48 as masks. This ion implantation creates P-type dopant diffusion areas 52 for extension in the silicon substrate 10 in such a manner that the diffusion areas put the basement of the gate electrode 48 for each P-type transistor between them ( FIG. 2N ).
- the N-type dopant diffusion areas 50 do not always have to be formed all at once; they may be formed separately in the high-voltage, medium-voltage, and low-voltage transistor formation areas, in any order. This applies to the P-type dopant diffusion areas 52 as well.
- Silicon dioxide or some similar material is deposited by CVD or some other method to cover the whole surface. Subsequently, an etch-back treatment is applied to the obtained film to form sidewall insulating films 54 that sandwich the gate electrodes 48 ( FIG. 2O ).
- a photoresist film is formed to cover the P-type transistor formation areas, leaving the N-type transistor formation areas exposed.
- An ion implantation is performed with this photoresist film, the gate electrodes 48 , and the sidewall insulating films as masks. This ion implantation creates N-type dopant diffusion areas 56 in the silicon substrate 10 in such a manner that the diffusion areas put the basement of the gate electrode 48 for each N-type transistor between them.
- a photoresist film is formed to cover the N-type transistor formation areas, leaving the P-type transistor formation areas exposed.
- An ion implantation is performed with this photoresist film, the gate electrodes 48 , and the sidewall insulating films 54 as masks. This ion implantation creates P-type dopant diffusion areas 58 in the silicon substrate 10 in such a manner that the diffusion areas put the basement of the gate electrode 48 for each P-type transistor between them.
- the N-type dopant diffusion areas 50 and 56 and the P-type dopant diffusion areas 52 and 58 are heated in a nitrogen atmosphere or under other similar conditions so that the dopants existing therein are activated. This treatment allows the N-type dopant diffusion areas 50 and 56 to include N-type source/drain areas 60 and the P-type dopant diffusion areas 52 and 58 to include P-type source/drain areas 62 ( FIG. 2P ).
- the method of manufacturing a semiconductor device according to this embodiment may also include salicide, multi-layer wiring, and other processes.
- the operation illustrated in FIG. 2F includes the substantially simultaneous removal of the silicon dioxide film 28 from the medium-voltage transistor formation areas and N-type low-voltage transistor formation area.
- the following explains the reason for this by comparing the above-described manufacturing method and another method of manufacturing a semiconductor device according to the embodiment. The latter method is described below for reference.
- the manufacturing method illustrated in FIGS. 3A to 3H , is another example of methods of preparing different kinds of MIS transistors with gate insulating films of different thicknesses.
- a silicon dioxide film 28 is formed to cover transistor formation areas ( FIG. 3A ).
- the film thickness reached is, for example, 10 nm.
- a photoresist film 30 is photolithographically formed to cover the high-voltage and low-voltage transistor formation areas, leaving the medium-voltage transistor formation areas exposed.
- the portions of the silicon dioxide film 28 lying on the medium-voltage transistor formation areas are selectively removed, with the photoresist film 30 as the mask, by wet etching with hydrofluoric acid or some other method ( FIG. 3B ).
- the photoresist film 30 is removed by ashing or some other method.
- the silicon substrate 10 is oxidized under heat by thermal oxidation or some other method so that a silicon dioxide film 32 is formed to cover the element formation areas in the medium-voltage transistor formation areas ( FIG. 3C ).
- the film thickness reached is, for example, 6 nm.
- oxidation proceeds also in the high-voltage and low-voltage transistor formation areas, which are covered with the silicon dioxide film 28 , increasing the thickness of the silicon dioxide film 28 to about 14 nm.
- a photoresist film 34 is photolithographically formed to cover the medium-voltage and high-voltage transistor formation areas, leaving the low-voltage transistor formation areas exposed.
- the portions of the silicon dioxide film 28 lying on the low-voltage transistor formation areas are selectively removed, with the photoresist film 34 as the mask, by wet etching with hydrofluoric acid or some other method ( FIG. 3D ).
- this method which involves the substantially simultaneous removal of the silicon dioxide film 28 from both the N-type and P-type low-voltage transistor formation areas, may possibly etch the element-partitioning film 12 to a greater extent in the P-type area than in the N-type area, as illustrated in FIG. 3D .
- FIGS. 4 and 5 illustrate plots of the time of treatment with hydrofluoric acid versus the resultant thickness of the silicon dioxide film 28 treated.
- FIG. 5 is an enlarged view of the area surrounded by a dashed square in FIG. 4 .
- the diamonds, squares, and triangles represent a plot for a sample that underwent no ion implantation (NON DOPE), a plot for a sample that underwent a series of ion implantations under the conditions of channel ion implantation for an N-type low-voltage transistor (LV NCH (In + /B + CHANNEL)), and a plot for a sample that underwent an ion implantation under the conditions of channel ion implantation for a P-type low-voltage transistor (LV PCH (As + CHANNEL)), respectively.
- NON DOPE NON DOPE
- LV NCH N-type low-voltage transistor
- LV PCH P-type low-voltage transistor
- the sample whose plot is represented by squares underwent the following series of ion implantations: an implantation with indium ions (In + ) at an accelerated energy of 100 keV with the number of ions implanted set at 1.0 ⁇ 10 13 cm ⁇ 2 , another indium ion implantation at 120 keV with the number of ions 1.0 ⁇ 10 13 cm ⁇ 2 , and an implantation with boron ions (B + ) at 15 keV with the number of ions 3.5 ⁇ 10 13 cm ⁇ 2 .
- indium ions In +
- B + boron ions
- the rate of etching of the silicon dioxide film 28 varied depending on the conditions of channel ion implantation. More specifically, etching of the silicon dioxide film 28 was much slower in the sample that underwent a series of ion implantations under the conditions of channel ion implantation for an N-type low-voltage transistor than in the sample that underwent no ion implantation, but was faster in the sample that underwent an ion implantation under the conditions of channel ion implantation for a P-type low-voltage transistor than in the sample that underwent no ion implantation. A similar influence was confirmed also for the rate of etching of the element-partitioning film 12 , which also received ions implanted thereinto at the time of channel ion implantation.
- the conditions of the slowest etching namely, those for the portion of the silicon dioxide film 28 lying on the N-type low-voltage transistor formation area, may cause a too fast etching or overetching in the P-type low-voltage transistor formation area, thereby allowing the element-partitioning film 12 to be etched to a greater extent in the P-type area than in the N-type area.
- the conditions of the fastest etching namely, those for the portion of the silicon dioxide film 28 lying on the P-type low-voltage transistor formation area, may cause a too slow etching or an insufficient removal of the silicon dioxide film 28 in the N-type low-voltage transistor formation area, thereby posing potential problems, for example, the gate insulating film 36 formed in a later operation with too great a thickness.
- the photoresist film 34 is removed by ashing or some other method.
- the silicon substrate 10 is oxidized under heat by thermal oxidation or some other method so that a gate insulating film, which is a silicon dioxide film, is formed to cover the element formation areas in all transistor formation areas ( FIG. 3E ).
- a gate insulating film 36 is formed with a thickness of, for example, 2 nm.
- a gate insulating film 38 is formed with a thickness of, for example, 14 nm.
- a gate insulating film 40 is formed with a thickness of, for example, 6.1 nm.
- oxidation proceeds also in the high-voltage transistor formation areas, which are covered with the silicon dioxide film 28 , and in the P-type low-voltage transistor formation area, which is covered with the silicon dioxide film 32 .
- the increase in film thickness brought about by oxidation is negligibly small for the silicon dioxide film 28 and as small as 0.1 nm for the silicon dioxide film 32 .
- a polycrystalline silicon film 42 or some other kind of conductive film that provides gate electrodes is formed by CVD or some other method to cover the whole surface. Note that the polycrystalline silicon film 42 has a bump corresponding to the difference in height between the element formation area and the element-partitioning film 12 .
- the polycrystalline silicon film 42 is covered by spin coating or some other method with a BARC film 44 and then a photoresist film 46 ( FIG. 3F ).
- the BARC film 44 may have a reduced thickness in the portion lying on the P-type low-voltage transistor formation area. The reason for this is as follows: In this area, some volume of the material of the BARC film 44 flows into the indentations formed on the element-partitioning film 12 and thus cannot reach the top of the bump, namely, the element formation area.
- the photoresist film 46 is photolithographically patterned to draw the intended pattern of gate electrodes ( FIG. 3G ). Because of the reduced thickness in the portion lying on the P-type low-voltage transistor formation area, the BARC film 44 has different degrees of anti-reflection effect in the P-type low-voltage transistor formation area and in the other areas. As a result, the exposure to light varies with position in the photoresist film 46 , and the resist pattern has accordingly different line widths and shapes in the P-type low-voltage transistor formation area and in the other areas.
- the polycrystalline silicon film 42 is patterned by dry etching, with the patterned photoresist film 46 as the mask. As a result, each transistor formation area holds a gate electrode 48 , which is based on polycrystalline silicon, formed thereon ( FIG. 3H ).
- the non-uniform geometry of the resist pattern such as different line widths, make the gate electrodes 48 have different lengths of gate in the P-type low-voltage transistor formation area and in the other areas.
- the operation illustrated in FIG. 2F involves the substantially simultaneous removal of the silicon dioxide film 28 from the medium-voltage transistor formation areas and N-type low-voltage transistor formation area. So, before the operation illustrated in FIG. 2H , or prior to the removal of the silicon dioxide film from the low-voltage transistor formation areas, the portion of the silicon dioxide film 32 lying on the N-type low-voltage transistor formation area is thinner than the portion of the silicon dioxide film 28 lying on the P-type low-voltage transistor formation area.
- the difference in height between the element formation area and the element-partitioning film 12 in the P-type low-voltage transistor formation area is much smaller in this method than in the method reference above, as can be seen from FIG. 2I .
- this method avoids thinning of the BARC film 44 in the portion corresponding to the element formation area of the P-type low-voltage transistor formation area, thereby reducing or preventing size variation among gate electrodes 48 .
- the element-partitioning film may be reduced or prevented from over-etching in the P-type low-voltage transistor formation area during etching operations in which the element formation areas have not been covered with a gate insulating film;
- the difference in height between the element formation area and the element-partitioning film is reduced in this area, and this solves problems such as electric field concentration on the edges of the element formation area, size difference among gate electrodes, and so forth;
- reliable semiconductor devices may be manufactured at a high yield.
- the combination of MIS transistors is not limited to the one specified in this embodiment, specifically, low-voltage, medium-voltage, and high-voltage transistors.
- the driving voltages of the transistors are not limited to those specified in this embodiment.
- the gate insulating film is a silicon dioxide film formed by oxidation of a silicon substrate; however, it may be a silicon nitride oxide film formed by oxidation followed by nitridation in a nitrogen-containing atmosphere.
- nitridation may be performed in one or some or all oxidation operations; it is acceptable to perform nitridation in any single operation, for example, the oxidation operation carried out to form the gate insulating film 36 for a low-voltage transistor.
- the rate of etching of a silicon dioxide film was faster in the P-type transistor formation areas doped with N-type dopant ions than in the N-type transistor formation areas doped with P-type dopant ions.
- the rate of etching does not necessarily conform to this relationship; different kinds of dopants may result in different relationships between these two areas in terms of rate of etching of the silicon dioxide film.
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JP2009275626A JP5526742B2 (en) | 2009-12-03 | 2009-12-03 | Manufacturing method of semiconductor device |
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JP5956809B2 (en) | 2012-04-09 | 2016-07-27 | ルネサスエレクトロニクス株式会社 | Manufacturing method of semiconductor device |
US9142566B2 (en) | 2013-09-09 | 2015-09-22 | Freescale Semiconductor, Inc. | Method of forming different voltage devices with high-K metal gate |
US10050033B1 (en) | 2017-09-13 | 2018-08-14 | Taiwan Semiconductor Manufacturing Co., Ltd. | High voltage integration for HKMG technology |
US11289598B2 (en) * | 2020-04-15 | 2022-03-29 | Globalfoundries Dresden Module One Limited Liability Company & Co. Kg | Co-integrated high voltage (HV) and medium voltage (MV) field effect transistors |
US11495660B2 (en) | 2020-11-06 | 2022-11-08 | Globalfoundries Dresden Module One Limited Liability Company & Co. Kg | Co-integrated high voltage (HV) and medium voltage (MV) field effect transistors with defect prevention structures |
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JPH08204025A (en) | 1995-01-20 | 1996-08-09 | Sanyo Electric Co Ltd | Manufacture of cmos semiconductor device |
JPH09181193A (en) | 1995-12-22 | 1997-07-11 | Sony Corp | Manufacture of semiconductor device |
US6764959B2 (en) * | 2001-08-02 | 2004-07-20 | Taiwan Semiconductor Manufacturing Co., Ltd | Thermal compensation method for forming semiconductor integrated circuit microelectronic fabrication |
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JPH08204025A (en) | 1995-01-20 | 1996-08-09 | Sanyo Electric Co Ltd | Manufacture of cmos semiconductor device |
JPH09181193A (en) | 1995-12-22 | 1997-07-11 | Sony Corp | Manufacture of semiconductor device |
US6764959B2 (en) * | 2001-08-02 | 2004-07-20 | Taiwan Semiconductor Manufacturing Co., Ltd | Thermal compensation method for forming semiconductor integrated circuit microelectronic fabrication |
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JP2011119470A (en) | 2011-06-16 |
JP5526742B2 (en) | 2014-06-18 |
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